java - 无法处理托管/反向引用 'defaultReference' : no back reference property found

Question

我有两个模型类。一个是

@Entity(name = "userTools")
@Table(uniqueConstraints = @UniqueConstraint(columnNames = { "assignToUser_id","toolsType_id" }))
@Inheritance(strategy = InheritanceType.JOINED)
@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "className")
@JsonIgnoreProperties(ignoreUnknown = true)
public class UserTools {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @OneToOne
    private ToolsType toolsType;

    @OneToMany(mappedBy = "userTools", fetch = FetchType.EAGER, cascade = { CascadeType.ALL }, orphanRemoval = true)
    @Cascade(org.hibernate.annotations.CascadeType.DELETE)
    @JsonManagedReference
    private List<UserToolsHistory> userToolsHistory;
}

第二个是

@Entity(name = "userToolsHistory")
@JsonIgnoreProperties(ignoreUnknown = true)
public class UserToolsHistory {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @OneToOne
    private ToolsType toolsType;

    @ManyToOne
    @JsonIgnore
    @JsonBackReference
    private UserTools userTools; 

    private String comments;
}

但是在保存时我收到了这个错误:

Can not handle managed/back reference 'defaultReference': no back
reference property found from type [collection type; class
java.util.List, contains [simple type, class
com.dw.model.tools.UserToolsHistory]]

Answer 1

为了方便排查问题，可以为@JsonManagedReference和@JsonBackReference分别添加不同的名称，例如:

@JsonManagedReference(value="userToolsHistory")
    private List<UserToolsHistory> userToolsHistory;

这样错误更有意义，因为它打印引用名称而不是“defaultReference”。

请指出您要序列化哪个实体 - UserTools 或 UserToolsHistory？无论如何，您可以尝试向您的实体添加 getter 和 setter，然后将 @JsonIgnore 添加到“child”类中的“get{Parent}()”。